Bone composition

# Bone consists of:
A. Two-thirds organic matter and one-third inorganic matrix
B. One-third organic matter and two-thirds inorganic matrix
C. One-half organic matter and one-half inorganic matrix
D. Two-thirds inorganic matter and one-third organic matrix

The correct answer is D. Two thirds inorganic matter and one-third organic matrix.

Bone consists of two-thirds inorganic matter and one-third organic matrix. The inorganic matrix

is composed principally of the minerals calcium and phosphate, along with hydroxyl, carbonate, citrate, and trace amounts of other ions, such as sodium, magnesium, and fluoride. The mineral salts

are in the form of hydroxyapatite crystals and constitute approximately two-thirds of the bone

structure.

The organic matrix consists mainly of collagen type l (90%), with small amounts of noncollagenous

proteins such as osteocalcin, osteonectin, bone morphogenetic protein, phosphoproteins, and proteoglycans.